qmmp is a Linux music player which will remind you of Winamp. In fact, it looks a lot like it and it can even use Winamp skins (as well as Xmms skins) so if you're just switching to Linux and can't give up WinAmp (although I really liked Foobar2000 on Windows but anyway), you should try qmmp as an alternative to WinAmp.
It supports mpeg1 layer 1/2/3, ogg vorbis, native flac support, musepack and wavpack, modplug, wmpa, pcm wave, acc. audio cds, CUE sheet, WavPack embedded CUE and FLAC embedded CUE support. It can use ALSA, PulseAudio, Jack or OSS sound. Of course, those are just the essential features. qmmp comes with basically all the features you would want in a music player (and even more).
One downside would be that qmmp is a QT application, but since it supports Winamp skins I don't think QT is a big drawback.
Other qmmp features include: